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SX - fort the Phillips, the link Butch provided is good. Unfortunately in all situations for the pre-fabbbed stuff they are still very pricey. If it's not, I would question it. As for the DIY, I guess it's a matter of factoring in time and effort and what you value that. The actual materials from what I've seen seem to be adequate so go for it!

Butch - interesting stuff, I only had time to glance at what you had tinkered with but I will definitely read more in depth later. So the full concept of what I am doing is looking at using Red and Blue Combinations as a supplemental light source for producing plug trays in greenhouses. We are attempting to provide roughly 100PAR and also have particular goals with DLI. I'm not sure exactly what all I can divulge since all this belongs to the University. We are using the distances from the light source provided to us by the manufacturer and are adjusting the power to get our desired PAR and overall DLI. Since this is for plug trays (not pretty house plants for intance) our criteria are a little different. We want our plants to have compact growth with short internodes and leaf petioles and highly developed root systems. We use the term pullability on whether plugs come out of the tray with the root system and soil intact. We are also looking at stem caliper and a specified quality index. We've noticed that all LEDs no matter what brand or type are subject to thermal degradation and have to be adjusted from time to time.

mobile - I've actually got an article somewhere talking about LEDs and horticulture and some of the broader goals of what is being sought for lights. Lemme dig it up and I'll post it later.

I've been doing a fair bit of internet research on LED grow lights recently. Lots of good stuff out there, but also a lot of misleading and/or contradicting information. Seems like the 'hot' subject in LED grow lights in recent times is the far-red band.

Butch, glad I answered your questions. I'm always happy to add as far as my own knowledge allows. I just finished a rep Tuesday and will be doing data analysis shortly. I'm looking forward to seeing the results of my labor!

mobile, Yes! Far-red is the up and up. I'm actually about to start a project with far-red and a combination of reds and blues... once I get everything setup which is a slow process since I'm the one that gets to do the setup and figure everything out from scratch. As for the misleading and/or contradicting information, there are a number of researchers that are currently working to develop a standard for LEDs in general and as plant lights. I am not familiar with their work specifically other than the fact that they are working to eliminate a lot of the bad information and keep people honest about their claims. I read your post on the CPUK forums. I am actually working with their growth chamber bars in a greenhouse (counter productive, I know). We're using them to develop a guideline for creating actual lights for the greenhouse setting.

I always throw lots or red at my plants under artificial lights. That's why I have a preference for warm white lamps. Far red is a little harder to achieve though until recently, but now there are LEDs in that band available. Incandescent lamps always had far-red of course, but with those there is the issue of heat.

Butch, Far red (Fr) light seems to be hit or miss for a lot of people both in and outside academia. I myself am still working on that knowledge with my literature review. Some say it's the coolest thing since sliced bread and others say it's inconsequential. So far from what I have read my conclusion is; it depends. It tends to delay certain physiological responds while improving other responses. For instance, I recently read a paper where Fr light enhanced the number of floral buds, but delayed the actual flowering.

At one point, it was said green light was of no use, but it's since been shown to have it's own purpose as well. It helps facilitate canopy penetration.

Incandescent lamps certainly still have perks which is why they are still being used in the Horticulture industry. With them being phased out, people are kind of scrambling for alternatives. CFLs got some use, but there is the even bigger issue of Hg and it has been found that the whole on/off cycle greatly reduces their lifespan. LEDs seem to be the next logical step (curtailing HID and HPS) lights, but we're still trying to figure out what really works. My research is specifically hoping to have lights developed specifically for greenhouses within the next year in trial in actual industry greenhouses. My fingers are crossed of course because I want to still be around for that!